feat(01-03): export all public APIs from package root

- Export error types (KBError, NetworkError, ValidationError, SystemError, AuthError, ErrorType)
- Export config (KBSettings, get_settings)
- Export retry (retry_on_network_error)
- Clean import interface for users

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

kb_pipeline/__init__.py

@@ -13,8 +13,19 @@ from .schemas import (
     StepDefinition,
 )
 from .state import WorkflowStateManager
+from .errors import (
+    KBError,
+    NetworkError,
+    ValidationError,
+    SystemError,
+    AuthError,
+    ErrorType,
+)
+from .config import KBSettings, get_settings
+from .retry import retry_on_network_error
 
 __all__ = [
+    # Schemas
     "StepInput",
     "StepOutput",
     "StepResult",
@@ -22,7 +33,20 @@ __all__ = [
     "StepRecord",
     "WorkflowState",
     "StepDefinition",
+    # State
     "WorkflowStateManager",
+    # Errors
+    "KBError",
+    "NetworkError",
+    "ValidationError",
+    "SystemError",
+    "AuthError",
+    "ErrorType",
+    # Config
+    "KBSettings",
+    "get_settings",
+    # Retry
+    "retry_on_network_error",
 ]
 
 __version__ = "0.1.0"